X Cloud Clusters¶

Target Storage Utilization¶

The Target Storage Utilization option defines the specific storage usage level the system aims to maintain. ScyllaDB Cloud monitors metrics and triggers scaling actions to stay as close to your target as possible.

• Default: 80%

• Maximum: 90%

We recommend adjusting this value based on your specific workload requirements:

• For write-intensive workloads, we recommend values below 85% to ensure timely scaling and avoid performance degradation related with scaling in the last possible moment.

• While higher utilization optimizes costs, it may trottle operations while scaling under load. For critical production workloads, lower targets provide a larger safety buffer for sudden spikes.

For example, with an 80% target, X Cloud will proactively add capacity as you approach that threshold and remove it when demand drops. For more technical details, see X Cloud Autoscaling Behavior and Best Practices.

Reserving Minimum Resources¶

The Minimum Physical Storage and Minimum vCPU Count fields are optional. You can leave them empty and allow ScyllaDB Cloud to scale resources dynamically based purely on workload.

However, if you have specific capacity requirements, you can set these minimum values to reserve capacity for anticipated load. Setting minimums ensures a baseline level of resources for your workloads. If your cluster is below the defined minimum capacity, it will scale up to meet those requirements. If the cluster is above the set minimums, it will not scale below this baseline. As a result, critical workloads remain stable even when traffic fluctuates.

These minimums can be adjusted at any time.

You can use the built-in calculators to estimate appropriate minimum values.

📱 Minimum Physical Storage Calculator¶

The storage calculator helps you estimate the minimum physical storage required based on the amount of data you plan to store at the start. It uses several factors to calculate the recommended minimum storage.

• Raw Data Size - The amount of data you expect to store in your cluster. It represents your dataset size before replication and compression.

• Replication Factor - X Cloud uses a fixed replication factor of 3, so your data is always stored in three copies across the cluster. This creates three replicas, one in each cluster zone. The total size of the data stored is multiplied by 3: Raw Data Size × 3.

• Compression Savings - ScyllaDB Cloud compresses the data, which reduces the actual disk usage. Compression reduces the total storage space required for your data.

  The compression savings slider represents how effectively your data can be compressed, which depends entirely on your data type. The examples below show typical compression savings for different data types:

  • High compression (50–80%) - Text-heavy data, such as logs, CSV, JSON or plain text documents

  • Medium compression (30–60%)) - Mixed data types, such as typical application data with a combination of text and binary fields, database, backups, snapshots.

  • Low compression (0–20%) - Already compressed data, such as binary data (images, videos) or encrypted data.

• Target Utilization - Defines the goal for cluster storage utilization. Autoscaling maintains this level by scaling the cluster up or down as needed. This ensures there is always enough capacity to handle compaction, repairs, and workload spikes without running out of space, while minimizing storage underutilization.

The calculator combines these factors to compute the recommended minimum physical storage for your cluster, using the following formula:

((Raw Data Size × 3) × (1- Compression Savings)) ÷ Target Utilization

📱 Minimum vCPU Count Calculator¶

The vCPU calculator helps you estimate the minimum number of vCPUs required based on your workload characteristics and estimated transactions. It uses several factors to calculate the recommended minimum compute capacity for your cluster.

• Instance Family - The instance family you choose for your cluster affects how much workload each vCPU can handle. Different instance families have different performance characteristics. You can view the estimated ScyllaDB-specific performance next to each instance family name in the UI.

• Reads per Second - The number of read operations your workload is expected to perform. Read-heavy workloads typically require more vCPU resources to maintain low latency and high throughput.

• Writes per Second - The number of write operations your workload is expected to perform. Write-heavy workloads can also demand more vCPU resources, especially if they involve complex operations.

• Schema Complexity - Reflects how complex your data model and queries are. More complex schemas and queries can increase the computational load on the cluster, requiring more vCPU resources to maintain performance. Choose the option that most closely matches your schema:

  • Simple – No indexes, up to 5 columns, basic queries.

  • Moderate – Includes a single advanced feature such as a secondary index, materialized view, or CDC.

  • Complex – Uses lightweight transactions (LWT) or multiple advanced features.

Instance Family and Type¶

The Instance Family and Instance Type options allow you to narrow down the instances to be used for auto-scaling:

• Instance Family - Specifies the instance family to be used for auto-scaling. X Cloud clusters are scaled automaticaly within one predefined instance family.

• Instance Type - Specifies instance types to be used for auto-scaling. By default, all instance types within a given family can be used when auto-scaling a cluster to optimize storage utilization and compute.

  ℹ️ Manually restricting the cluster to specific instance sizes can limit the effectiveness of the autoscaling engine. We strongly recommend using the default Any setting to allow the system to choose the most efficient instance types for your current scale.

Initial Deployment Summary¶

After you customize the auto-scaling policy, the Initial Deployment summary will show:

• Deployed Physical Storage - The total initial amount of physical storage allocated to all nodes in the cluster.

• vCPU - The number of vCPUs.

• Availability Zones - The availability zones with the instance type configuration for each zone. The cluster consists of three zones with automatic data replication, each with the same instance type configuration. By default, each cluster zone is deployed in a different cloud availability zone. You can customize the availability zones for your cluster, but we recommend that you deploy each zone in a different cloud availability zone to ensure high availability. See Configure Availability Zones for details.

Updating Auto-Scaling Policy for an Existing Cluster¶

To modify the auto-scaling policy for an existing cluster, go to your cluster’s page and click Edit Scaling Policy.